Abstract: A power brush housing assembly formed by a wheeled chassis with a housing overlying the chassis and fixed thereto bears transversely, an elongated scrubbing brush roller, and a motor for driving the brush roller to scrub the surface traversed by the power scrubber. A triangular shaped vacuum recovery head is hinge mounted to the face of the housing to permit tilting of the head from its normal vertical orientation to an inclined orientation and to effect movement of the mouth of the vacuum recovery head away from the surface being scrubbed to permit the power scrubber to move over minor obstructions.

Abstract: An automatic door closer constructed for releasably holding a door in a predetermined partly open position mainly comprises a piston arranged in a cylinder bore of a housing and operatively connected to a closer shaft mounted in the housing turnable about an axis substantially normal to that of the cylindrical bore so that the piston will be reciprocated in the bore during turning of a door connected to the closer shaft. The piston divides the bore in the housing in two compartments filled with fluid and a coil compression spring in one of the compartments biases the piston to an end position corresponding to the closed position of the door. The piston is provided with two passages therethrough, in one of which a one-way valve is arranged permitting flow of fluid only from the one compartment into the other during movement of the piston in door opening direction.

Abstract: A body of a butchered animal suspended at its hind legs by suspension conveying means is conveyed by means of a conveying table to a station for splitting the body into two halves along the spine, where the body and the conveying table become stationary and the body is turned through 90 degrees in a splitting position between body supporting means and pusher means which is indexed with the conveying table, so that the back of the body will face the body supporting means. Then, sensing means senses the presence of the body in the splitting position and actuates the body supporting means to bring it to an operative position to support the body, while the pusher means is also actuated to urge push rods extending through the conveying table into contact with the body to clamp it tightly to the body supporting means.

Abstract: The invention relates to a simplified wire snap formed of a bent piece of wire made of a high tensile steel material. The wire snap is formed by bending a length of wire at its extremities so that the bends face back toward one another and on a central body of the wire therebetween. The extremities of the bent wire have hooks therein and the hooks are directed in opposite directions with offsetting or angular bends therein to permit the wires to be readily bent and fit around the main body portion to secure to the same. The hook extremity of one bend portion overlies or extends beyond the hook extremity of the opposite bent portion to significantly increase the tensile strength of the wire snap.

Abstract: A clamp assembly for fixedly supporting a tube is disclosed herein and includes a main body member, a secondary body member and a locking member, the latter maintaining the two body members in an interlocked tube supporting position. The locking member is integrally formed to include a shaft, an enlarged head at one end of the shaft and a crossbar at the other end of the shaft. This integral member is interlocked with the secondary body member of the clamp assembly regardless of its position with respect to the main body member, as provided by a special hand tool.

Abstract: The temperature of a heating fluid used in a yarn crimping zone is controlled in response to whether a yarn plug is detected at a predetermined point, and in another embodiment a fluid is heated, passed to a yarn heating zone and a yarn is heated in the zone in response to whether the yarn is being wound in a yarn winding zone.

Abstract: A gas panel fabrication method includes forming a first set of dielectrically coated parallel conductors on a glass plate, forming a metal spacer layer over the first conductors, oxidizing those areas of the metal spacer layer which are between the first conductors, forming a second set of dielectrically coated parallel conductors over the spacer layer in orthogonal relationship with the first conductors, etching the unoxidized areas of the spacer layer from between the second conductors, and forming a cover plate to hold an ionizable gas adjacent to the orthogonal conductors.

Abstract: A rotary cylinder for use in a calender has a roller with a hollow cylindrical sleeve and two trunnions secured to the end portions of the sleeve. The roller contains a coaxial displacing component which defines with the sleeve an annular clearance for the flow of a cooling or heating fluid, such fluid being admitted through one of the trunnions and being evacuated through the one or the other trunnion. One or more prestressed elastic cushions are interposed between the displacing component and the roller to compensate for and to counteract eventual radial and or axial movements of a portion of or the entire displacing component as a result or unequal heating or cooling of the roller and displacing component. A single cushion may constitute a hollow conical frustum or a hollow cylinder. If the roller contains several cushions, such cushions may constitute discrete disks or ribs which are integral with the displacing component and contact the internal surface of the sleeve.

Abstract: A hollow valve body having two hubs for connection to a piping system and containing a spherical plug or ball is constituted by two shells cut from pipe sections. Each shell is shaped so as to form a flared-out portion in a spherical zone, the edge of which is provided with a semicircular notch. A sleeve having a recess at the inner end so as to form a valve seat is welded in position within one of the hub connections. The ball is enclosed between the two shells which are joined together by welding. A second sleeve also provided at the inner end with a valve seat is welded in position within the other hub connection. A stuffing-box is engaged on the ball-operating rod and welded to the orifice formed by the two oppositely-facing semicircular notches.

Abstract: Disclosed is an improved puller especially adapted for removing pulleys from the shafts of engines such as lawn mower engines, small tractor engines, etc. The puller comprises generally a box-like member of heavy steel plates with one open wall. A jack screw is threadedly associated with one wall and a pulley, mounted on the shaft, is adapted to be received in position for operative thrust engagement with an opposite wall. Running in on the jack screw forces the hub or central portion of the pulley into operative thrust contact with the opposite wall, whereby the shaft is moved axially of the pulley, thus effectively removing the pulley without damage.

Abstract: A cradle is mounted on a frame for pivotal movement about a horizontal axis between a start position and a discharge position. In the start position the pallet stringers are placed in the cradle and supported by upright guides including transverse, spaced guide bars. The stringers are clamped longitudinally. A first set of deck boards is placed across the stringers and fastened to them. The cradle is unlocked and rotated to the discharge position to thereby turn the partial pallet over. The other set of deck boards is then placed between longitudinal guide bars that had supported the stringers, and these deck boards are fastened to the stringers. The clamp is released, and the completed pallet falls under gravity free of the cradle which is then turned back to the start position for a new pallet.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: An addition material in powder or particulate form comprising at least one addition agent selected from the group consisting of calcium, magnesium and aluminum is extruded to provide a compact core wire, which is enveloped by a tape of iron or steel. The tape is circularly shaped such that one widthwise marginal portion is folded tightly over the other widthwise marginal portion in overlapping relation. The tape thus shaped serves as a protective covering for the core wire. Great lengths of continuous wire can be manufactured by the continuous production process. The wire shaped composite addition material produced in this way is added to molten iron and steel by means of continuous wire feeding and hereby provides for effective deoxidation and desulfurization of such melts. Furthermore the linear additive is easy to handle and to store.

Abstract: A gutter construction for the periphery of swimming pools is formed of at least two prefabricated members joining together. First is a main gutter member which is molded from a longitudinally slit, plastic cylindrical material and includes a vertical rear wall and a horizontal bottom wall extending forwardly from the lower edge of the rear wall. A front rim member is also molded from a tubular plastic material and has the lower wall thereof secured to the upper surface of the main gutter member near the front or free edge thereof. A perforated gutter cap rests atop the upper edge of the rear wall of the main gutter member and the juncture of the lip and rear wall of the tubular member which forms a seat for the front edge of the gutter cap. All of the members, i.e.

Abstract: Powdered plastic encapsulation of solid tantalum capacitors is achieved through coating the capacitors between 150.degree. C. and 250.degree. C. while biasing the capacitors at direct voltage between 0.2 and 1 times the rated voltage. The plastic is cured in about 3 minutes. The capacity temperature derating and the reverse current temperature derating are reduced with respect to capacitors encapsulated unbiased at the same temperature.

Abstract: In a semiconductor integrated circuit device composed of insulated gate field-effect transistors, the improvement comprises the fact that insulated gate field-effect transistors having gate insulating films of substantially equal thicknesses are arranged on a principal surface of a semiconductor substrate in the shape of a matrix. Gate input columns of the transistors are formed of polycrystalline silicon layers, and some of the transistors are enhancement type, while others are depletion type. Further, the respective transistors are formed by the self-alignment technique which employs the polycrystalline silicon layers as a diffusion mask, and the depletion type transistors are formed by implanting impurity ions opposite in the conductivity type to the substrate into selected areas of the surface of the substrate. Thus, a read only memory in a MOS-IC chip has its occupying area reduced remarkably.

Abstract: A method for fabricating a field-effect transistor device is provided with the device resulting having a relatively substantial capability to withstand reverse bias voltages. The device can also be provided having a relatively low "on" condition resistance between the source and drain terminals thereof by virtue of a geometrical design choice.

Abstract: An expansion joint for metallic foil strip heaters encasing resistive heating elements comprised of a bend formed in the metallic foil strips. The expansion joint is formed by use of a tool for passing a roller in the tool handle over a rigid forming support affixed to the tool bottom forming plate with the metallic foil strip heater placed between the roller and the forming support. The tool is then removed and a flexible metal support hose is affixed to the object to be heated with the bend in the metallic foil strips placed over this support hose. The bend is then affixed to the object to be heated on either side of the support hose.

Abstract: A tube guide-expander for guiding heat exchanger tubes through tube sheet apertures from a secondary to a primary side thereof and expanding those tubes into contact with the apertures' walls. The guide-expander includes relatively axially displaceable first and second compression structures and elastomeric O-rings which radially expand into contact with the tube's inner surface when axially compressed between the compression structures. The first compression structure is abuttable with the tube's end and has an axial opening therethrough. The second compression structure constitutes an elongated element which extends through the opening and has a ram element connected to the end inside the tube and a driving element connected to the end outside the tube. The ram and elongated elements are preferably threadably engaged so as to permit relative axial displacement therebetween when they are relatively rotated.

Abstract: In the production of varistors, diode chips are cut from a p-n sheet-diffused semiconductor wafer. Instead of having conventional rectangular shapes, the chips have a rhomboidal shape. This makes the shape of the chips asymmetric in that one surface of each chip becomes a distinguishable mirror image of its other surface. The direction of the p-n junction in the wafer is oriented with respect to the shape of the chips to be cut to place the same conductivity type region adjacent to the same rhomboidal shape of the surface. As a result, the polarity of the chips, or the direction in which the p-n junctions are oriented within the chips, becomes identifiable by the shape of the chips. This substantially aids in sorting, inspecting, assembling and other handling operations performed on the chip. The chips can, for instance, be inspected visually to determine whether the p-type or the n-type doped portion of the chips are facing away from a supporting surface.

Abstract: A method and apparatus for making an electrical harness. The harness generally includes at least one connector having a housing with insulation displacement type contacts loaded therein. Each contact is connected to an insulation clad wire, said wires being of different lengths with different segments of insulation removed from the wire ends opposite the connector.

Abstract: A guard member is secured at one end adjacent the pivot point of a pair of scissor blades having opposed cutting edges. The guard member extends away from the cutting edge at an acute angle and downward to form a narrow slot at the outside edge of the cutting blade forming an open space between the guard member and a substantial portion of the cutting edge.

Abstract: An attachment for a typical saber saw to allow the depth of cut of the saber saw to be varied. The attachment includes a parallelogram-type member for attachment to the underside of the base plate of the saber saw and an adjustment member for varying the overall thickness or height of the parallelogram-type member whereby the depth of cut of the saber saw is effectively varied.

Abstract: A device for measuring the thickness of coatings comprises a rotatable drill, the cutting edge or edges of which are at a 45.degree. angle to the axis of the drill. The drill is manually operated by means of a finger disc and guided and steadied during its operation in a through-going bore in a guide plate resting with an anti-slide surface on the coated surface, the thickness of whose coating is to be determined. The conical cut made by the drill is observed in a microscope, and the width of the circular band is noted on an in-built micrometer scale. Owing to the cutting angle being 45.degree., the said width is equal to the thickness of the coating.

Abstract: Apparatus for precisely positioning a workpiece in a measuring machine having a pair of intersecting reference axes by using first and second physically identifiable workpiece reference points positioned at known locations relative to a workpiece zero line. The apparatus includes a clamp plate (20) on which the workpiece may be mounted, a bearing structure (36,37) for supporting the clamp plate (20) for uniplanar motion and a centering pin and carrier (60) for constraining the clamp plate to pivot about one of the workpiece reference points. A centering spindle (7) supported on the machine may be used to locate accurately the workpiece reference points and thereby to position accurately the workpiece zero line relative to the intersecting reference axes of the measuring machine.

Abstract: A system for inspecting the relatively long, thin-walled, small-bore tubes of a heat exchanger provided with support plates for holding the tubes in predetermined positions, comprising a composite scanner having a plurality of flexure springs contacting the interior surface of a tube for detecting and profiling tube abnormalities as the scanner traverses the tube and an eddy current sensor for generating a unique signal as the scanner passes a contiguous support plate to assist in the accurate location of tube abnormalities.

Abstract: A measuring while drilling tool is disclosed. The preferred embodiment incorporates an outer shell which is connected in a drill string above the drill bit and among the drill collars. The apparatus utilizes mud pressure variations to pump oil with a piston to energize a closed hydraulic circuit. The oil is delivered via a distribution and manifold system to first fill and scan five hydraulic signals sequentially. The sequential scan of the five hydraulic signals is then conveyed to an output mechanism comprising a choke which is placed in the lower end of the tool which choke varies the mud throughput, thereby varying upstream pressure in the mud circuit, forming an output which can be detected at the surface.

Abstract: A device for drawing parallel lines both in vertical and horizontal directions, and for drawing circumferences without a compass, includes two pieces, one of which is a set square and the other of which is a plate. Two adjacent edges of the plate are provided with markings, such as a millimetric scale, and groups of holes are distributed in relation to the markings of the indicated scale.

Abstract: A housing having propeller type fans in the housing adjacent to an object or objects to be dried. Shafts, carried by sleeves projecting through the side walls or top wall, rotate the fans. Motors externally of the housing drive the shafts.In one form of the invention, the air circulated by the fans is heated by steam coils adjacent to the periphery of the blades of the fans. In another embodiment, an open flame gas or oil burner, disposed in a combustion chamber, heats air, which is subsequently directed by ducts to the fans. Exhaust blowers and exhaust ducts exhaust the fume laden air from the chamber. Still another embodiment shows pairs of juxtaposed oppositely blowing fans carried by shafts protruding through the walls of the oven and spaced heaters between the fans. Still another embodiment shows opposed fans for drying a cylindrical member passed through the chamber.

Abstract: An apparatus for producing a treatment bed with a fluidized, circulating medium comprises a fluidization container having intake means for a fluidization agent and means for vibration in the longitudinal direction comprises a fluidization grid consisting of a plate having a plurality of vents arranged in rows alternating with a plurality of rectilinear unvented strips, the strips being parallel to the vertical plane containing the direction of the vibrations.

Abstract: A knee joint for an anthropomorphic dummy for use in motor vehicle crash testing comprises a femur member with a cylindrical pivot bearing, a tibia member with a cylindrical socket bearing having a radius greater than that of the pivot bearing, resilient locating strip between the pivot bearing and socket tending to restore the same to a substantially coaxial relationship and a plurality of pivotably linked arms defining a parallelogram having one side centrally pivotably mounted coaxially with the pivot bearing and the two opposite apexes pivotably connected to the tibia member. The arms allow rotation of the tibia with respect to the femur and further allow shearing translation therebetween only in a direction substantially perpendicular to the tibia member.

Abstract: An elastomeric shoesole designed specifically for athletic activities wherein the sole contains at the outer side of the heel and/or the inner side of the ball transversely-extending, longitudinally-spaced openings which extend to approximately the longitudinal center line and wherein the respective opposite sides are substantially solid, thereby allowing the sole to yield at the outer side of the heel end to a greater extent than at the inner side and at the inner side of the ball to a greater extent than at the outer side.

Abstract: Air permeable wear-resistant insoles comprising a web or matt layer of fibres, bonded with active carbon and bonded thereto a wear-resistant fabric which is different from and has greater wear-resistance than said web or matt layer, in which the ply bond strength of the said bond between the wear-resistant fabric and the said matt or web layer is greater than the ply bond strength of the matt or web layer itself, said insoles being produced by forming a web or matt of fibres loaded with active carbon by an air-laying method onto a wear-resistant fabric, impregnating the web or matt of fibres with a latex binder and effecting migration of the binder from the interior of the web or matt to the surfaces thereof and curing the binder to form an air permeable insole.

Abstract: An orthotic stabilizer for an athletic shoe comprising a semirigid body formed to fit around and under the wearer's heel above the midsole forming a concave pocket for receiving the heel and extending from the heel along approximately two-thirds of the length of the foot. Immediately beneath the calcaneous region is an opening in the stabilizer approximately the size of the calcaneous lower extremity filled with a padding material. The stabilizer serves to cushion the calcaneous during running and expedite subtalar joint stabilization to allow the foot to accommodate to the running surface as heel contact is made.

Abstract: A machine for cleaning debris from railway roadbeds, particularly from between rails of a single track and the space between tracks in railroad yards, comprises an articulated tractor and scraper-loader, each preferably having only two wheels. The scraper-loader has a scraper blade which extends transversely to the track when the machine is in use and a notch which loosely fits over a rail. The blade has wings extending oppositely from the notch. One of the wings has a length which is substantially equal to, but no greater than, the distance between the rails of a track, and the other has a length equal to at least one-half of that distance. The blade has a shoe which overlies the notch and which rides on the surface of a rail to establish the depth of the blade relative to the rails. The shoe is adjustably mounted on the blade so that such depth can be varied in order to clean between the rails of tracks which have rails of different heigths above their ties.

Abstract: Disclosed herein is an assembly in two parts with which to construct frames for pictures, prints and photographs, et cetera.The said two component parts are: a wooden or similar or plastic material strip that extends longitudinally and is essentially rectangular in shape, this having over the full length thereof a slit that is also rectangular; and an essentially V shaped body that can be elastically deformed and is provided with two U shaped limbs, each of which defines a tooth.With this particular assembly it is extremely easy both to insert the subject to be framed and to eventually replace it with another.

Abstract: An index tab is disclosed which attaches over a corner of a sheet or several sheets of paper. The tab includes a tubular body which has a paper enclosing portion receptive to a triangular corner portion of the sheets of paper and a projecting portion which projects from an edge of the sheets of paper. The index tab is attached to the papers by means of a single staple which penetrates both the paper enclosing portion of the body and the corner of the sheets of paper so that the same staple which holds the paper together, also attaches the index tab thereto.

Abstract: A cooperating arrangement of two side panels and a middle interconnecting panel therebetween forming a self-standing display due to the H-shape presented by the bottom edges of said panels in relation to a floor or support surface, and wherein from said erect condition the panels fold into a more compact condition more suitable for storage and shipment of the display.

Abstract: A portable sign of a lightweight plastic, unitarily constructed, having a raised face with selected portions indented therein to provide a preselected message thereon. For example, when the portable sign is used as a signaling device, the sign is provided with a handle thereon unitary with the sign and the indentations spell out a specific signaling indicia, such as, "STOP" or "SLOW".

Abstract: A removable sign post holding apparatus including a body portion having a post-receiving opening, a plurality of ground-engaging sections extending downwardly from the periphery of the body portion, a connector section extending outwardly from the said body portion, an opening in the connector section, a removable cap portion engageable with the post-receiving opening of the body portion, the said cap portion including an anvil section of a size larger than the opening of the body portion, a plurality of flange sections extending from the anvil section, the flange sections being of a length adjacent the anvil section to mate with the corresponding portion of the body portion with which it is engageable.

Abstract: An automatic fish snagger has a tiltable, spring-loaded tube for receiving the handle of a fishing rod, the tube being normally "cocked" through use of a latch which is tripped as the result of a tug on the line by the fish. The spring then swings the tube, and therefore the rod, in a direction to "set" the hook. The geometry of the device is such that when making one or more of a number of adjustments, the fisherman can be assured of a catch under various conditions whenever the fish either "strikes" or takes the bait, all before the bait can be ejected from the mouth upon discovery of the hook.

Abstract: An apparatus for signaling if a fish bites a fishing line. The apparatus includes a housing containing a contact bar and an arm. The contact bar and arm are connected to a battery powered electrical circuit that sounds an alarm and energizes a lamp if they contact each other. The arm is biased into contact with the contact bar in the normal state. A cord is secured between the end of the arm and the fishing rod. The fishing rod is positioned by a rod holder so that it maintains enough tension in the cord to draw the arm out of contact with the contact bar. Should a fish bite, the end of the rod will dip, releasing enough tension for the arm to contact the contact bar to cause a signal which may be both visual and audible.

Abstract: A fish line sinker includes an elongated sinker body having a central longitudinal opening extending therethrough and having a longitudinally extending slot open from one end of the central opening to the other to the outside of the sinker body. A fish line retaining clip has a pair of ears, each one pivotally mounted with respect to one of the ends of the central opening in the sinker body, the retaining clip having a longitudinally extending bow integrally connected between these ears. Each ear is provided with a fish line receiving slot outwardly positioned on it, the slot being of shape and size to receive a fish line and to position the fish line within the sinker body central opening when the retaining clip is aligned on the sinker body opposite the longitudinally extending sinker body slot, the fish line receiving slots in the retaining clip ears being of shape and size to confine the fish line within the body central opening when the clip is aligned with the body slot.

Abstract: An animal trap is disclosed. The trap comprises a frame, a stationary jaw mounted on the frame, a movable jaw pivotally mounted on the stationary jaw, springs, interconnecting the frame and the movable jaw for moving the movable jaw in contact with the stationary jaw, a trigger element interconnecting the frame and the movable jaw, such trigger element being in the shape of a flat strip having the ends thereof slightly curved inwardly to hold the frame and the movable jaw together when the trap is set, and a bait holder depending from the trigger element whereby a slight displacement of the bait by an animal will disengage the trigger element from the movable jaw to release the trap.

Abstract: A play doll house and furniture puzzle combination includes a plurality of pieces of furniture all of which have at least one common dimension and a play doll house having an interior space with a length equalling the common dimension of the furniture but wide and tall enough to contain all the furniture when fitted into the space in predetermined puzzling nesting relation, with the common dimension of each piece along the length of the play doll house; in preferred embodiment the play doll house has interior congruency type markings on the front wall providing a first, or easy mode of assembly; a symmetrical gable roof defining the upper part of the space, which is accessible through double, outside-hinged doors at the rear of the house, prevents the space from being rectangular and limits other possibilities of assembly to a second or harder mode of assembly which is 180.degree.

Abstract: A model airplane comprises a flat wing and a member connected to the wing midway between the wing-tips and near the back of the wing which extends away from the top surface of the wing. A freewheeling vane is connected to the back of the member and spaced-apart from the top surface of the wing.

Abstract: A figure toy having appendages of a soft plastic. The toy is covered front and back on its body and appendages with suction cups so that it will adhere to various smooth surfaces at its front, back, and appendages.

Abstract: A manipulative hand puppet in which an object is fastened to the puppet by a flexible elastic string. A flexible hook patch and a flexible pile patch are provided. One patch is secured to the outer surface of the puppet and the other is secured to the outer surface of the object. The puppet is manipulated by grasping the object and tossing the object away from the puppet. The string is thus extended and this causes the object to move back to contact with the puppet, whereupon the patches mate and the object is caught and held to the puppet until again grasped and tossed away from the puppet. Various embodiments simulate a baseball player puppet playing with a baseball object, a football player puppet playing with a football object, and a dog puppet playing with a bone-shaped object.

Abstract: A method for cultivating an alga, which comprises growing the alga in a light field substantially free from light of wavelengths of not more than 340 nm; and a covering material for use in the cultivation of algae, said covering material substantially inhibiting the transmission of light of wavelengths of not more than 340 nm.

Abstract: A synthesis gas stream having a H.sub.2 /CO ratio of less than 3/1 is split, with one stream being subjected to water gas shift essentially to completion, adjusted with a portion of the other stream to a carbon monoxide content of about 3-6% by volume, and reacted in an adiabatic methanation zone. The high hydrogen composition and high H.sub.2 /CO ratio of the stream passed to the adiabatic zone is effectively regulated in this manner, preventing carbon formation and catalyst sintering. The effluent from said adiabatic zone is mixed with the remaining portion of the other stream and passed to an isothermal methanation zone. Carbon dioxide can be removed from the product methane-rich gas or from the methanation feed gas. In preferred embodiment, high pressure superheated steam is simultaneously produced by utilization of the heat of reaction of the methanation operations, enhancing the overall efficiency of the synthesis gas production-methanation operation.